Locking plate



J. S. PlTlSCl LOCKING PLATE May 10, 1949.

Filed March 6, 1945 INVENTOR. .JEIEEF'H ELFITIEEI.

7 ATTEIRNL'Y Patented May 10, 1949 LOCKING PLATE.

Joseph S. Pitisci, Miami Springs, Fla., assignor to Wright Aeronautical Corporation, a corporation of New York Application March 6, 1945, Serial No. 581,224

Claims. 1

This invention relates to locking means and is particularly directed to a locking plate structure adapted to simultaneously look a plurality of nuts, bolts, cap screws or the like.

The invention as illustrated is designed for locking the cylinder-hold-down cap screws on a radial-cylinder air-cooled internal combustion engine. In the conventional construction of such an engine, each cylinder is provided with an annular flange, adjacent its base, and the cylinder is secured or held down to the engine crankcase by cap screws extending through said flange and threaded into the engine crankcase. A plurality of such cap screws are generally locked together in position by threading a locking wire through holes in their heads. This locking operation is quite tedious and time-consuming because the cap screws are disposed adjacent to the base of the cylinders and therefore access to them is quite difiicult. This is particularly true in modern tworow radial-cylinder aircraft engines. Accordingly, it is an object of this invention to provide a new and improved means for locking such cylininder-hold-down cap screws, whereby said cap screws may be more readily locked.

Although the structure of the locking plate. as illustrated on the drawing hereinafter referred to, has been specifically designed for locking the cylinder-hold-down cap screws on an internal combustion engine, the invention obviously is not so limited but may be used wherever it is desired to lock a plurality of nuts, bolts, cap screws or the like. Accordingly, as hereinafter used in the specification and claims, the term nut is intended to also include bolts, cap screws and other machine elements having non-circular heads which it is desired to lock against rotation.

Specifically, the invention comprises a locking plate having a plurality of circuar holes therethrough, the holes having a spacing corresponding to the spacing of the cylinder-hold-down cap screws to be locked thereby and the plate being adapted to be placed in position over the cap screws with the cap screw heads extending through said holes. Each of said locking plate holes has a diameter somewhat smaller than the largest diagonal across the associated cap screw head whereby, when the plate is forced over the cap screw heads, the corners of the heads deform the holes to an out-of-round condition thereby preventing relative rotation between each cap screw head and the lock ng plate.

It is realized that locking plates have been used in the past for locking nuts but in the prior art practice each of the holes in the plate is shaped to conform to the shape of the nut to be locked. Therefore, with this prior construction, it is necessary to tighten the nuts to a predetermined rotative position in order to aline the corners of each nut with the corners of the corresponding hole in the locking plate. Accordingly, the use of such a prior art locking plate makes it unlikely that each nut can be tightened to the proper extent and instead, in all probability, each nut must either be tightened too much or too little in order to obtain the necessary alinement of the nuts with the holes in the locking plate. This limitation on the use of prior art locking plates is particularly undesirable on a device where the nuts are to be tightened with a predetermined torque, as are the aforedescribed cylinder-hold-down cap screws. In contrast with this prior art construction, with the locking plate of the present invention each nut may be tightened to any desired extent and there is no necessity for alining the corners of the nuts with any portion of the looking plate.

Other objects of this invention will become apparent upon reading the annexed detailed description in connection with the drawing in which:

Figure 1 is a perspective View illustrating the locking plate of this invention in connection with the cylinder-hold-down cap screws of an internal combustion engine;

Figure 2 is a plan view of the locking plate blank;

Figures 3 and 4 are plan and end views, respectively, of the locking plate in its final form;

Figure 5 is a plan view of the locking plate in operative position; and

Figure 6 is a sectional view along line 6-6 of Figure 5.

Referring to the drawing, a conventional aircooled internal-combustion-engine cylinder, illustrated in part at 40, is secured to the engine crankcase l2 by cap screws I4 which extend through holes in an annular flange l6 on the cylinder Ill and-which cap screws are threaded into the crankcase. As is conventional practice, each of the cap screws I4 is tightened by the application of a predetermined torque thereto. Locking plates i8 are provided for locking the cap screws l4. As illustrated, each locking plate is designed to lock five cap screws but. obviously, each locking plate may be designed to look any plural number of cap screws.

Each locking plate I8 is made from a blank 20, illustrated in Figure 2, having a scalloped edge 22 shaped to clear the perimeter of the cylinder adjacent the cap screws. Each blank 20 is provided with a plurality of circular holes 24 drilled therethrough at a spacing corresponding to the spacing of the cap screws to be locked thereby. The edge of each of the holes 24 is then pressed or formed to provide an annual axially-extending flange 26 thereabout, thereby completing the locking plate, as illustrated in Figures 3 and 4. Each said flange 26 is curved in a radial section and tapers inwardly such that its minimum diameter is at its end remote from the plate I8. The diameter of the holes 24, prior to said flangeforming operation, is such that after the holes are formed with the flange 26, the diameter of the holes through the locking plate I8, 1. e. at the outer ends of flanges 25, is smaller than the maximum diagonal across the heads of the cap screws.

The locking plate I8 then is adapted to be forced over the heads of the previously tightened cap screws I4 as illustrated on Figures 1, 5 and 6 whereupon the corners of the cap screw heads dig into the annular flanges 26. That is, as the looking plate I8 is forced over the heads of the cap screws I4, each flange 26 is deformed or distorted from its initial circular periphery by the angular corners of said heads to be locked thereby, as illustrated at 26' in Figure 5. As a result of this deformation of the annular locking plate flanges 26 about the cap screw heads, the cap screws are locked against rotation relative to the locking plate I8 and cylinder I0. After the locking plate is in position over the cap screws, a cotter pin 28 may be inserted through a hole in the projecting portion of one of the cap screw heads in order to prevent accidental displacement of the locking plate from the cap screw heads.

With this locking plate construction, each cap screw I4 may be pro-tightened to any extent before the plate I8 is forced into locking position over the heads of the cap screws. That is, with the present invention it is not necessary that the corners of the cap screw heads occupy some predetermined rotative position before the locking plate can be placed in locking position.

The locking plates I8 may be forced into position over the heads of the cap screws by a suitable tool, for example by a tool having a head adapted to engage the locking plate and having holes adapted to receive the cap screw heads as the tool forces the locking plate thereover.

Locking plate I8 may be made of any suitable material. A thin stainless steel plate, approximately .02" in thickness, has been found to be satisfactory but obviously the actual thickness of the plate depends on the particular material used. Also, it has been found satisfactory to drill the holes 24 to approximately 1% of an inch diameter, before forming, for locking cap screws with hexagon-shaped heads in which each head has a minimum width (across flats) of approximately .50" and a maximum width (that is on a diagonal) of approximately .60". Obviously, the size of the drilled holes 24 may be varied within reasonable limits, e. g. their size will depend on the particular material used and on the manner in which the flanges 26 are formed. However, the minimum diameter of the openings through the locking plate, after the flanges 26 are formed, should be less than the maximum width of the cap screw heads to be locked thereby. Also, after the flanges 2 6 have been formed, it is preferable that the minimum diameter of the locking plate openings not only be less than the maximum width of the cap screw heads but also be greater than the distance across the flats of said heads.

At this point it is again emphasized that this locking plate invention is not limited to lockin .cylinder-hold-down cap screws but may be used for locking any plural number of nuts, bolts, cap screws, etc. In addition, the shape of the locking plate and spacing of the locking plate holes obviously depends on the structure of the mechanism on which the plate is to be used.

While I have described my invention in detail in its present preferred embodiment, it will be obvious to those skilled in the art, after understanding my invention, that various changes and modifications may be made therein without departing from the spirit of scope thereof. I aim in the appended claims to cover all such modifications.

I claim as my invention:

1. A locking plate for securing, against rotation, a plurality of pro-tightened nuts or the like each having an angular periphery, said plate having a plurality of spaced rounded holes therethrough and having an annular flange about each of said holes extending from one side of said plate, each of said flanges converging away from the plane of said plate so as to have a minimum internal diameter at a point spaced from said plane, said minimum diameter of each flange being less than the maximum Width across the corners of a nut to be locked thereby and the material of each flange being such that said flange is distorted by the angular periphery of one of said nuts, in any rotative position of said nuts, as the plate is forced thereover, so as to interlockingly engage said nuts.

2. The method of securing, against rotation, a plurality of fixedly-spaced pre-tightened polygonal nuts or the like by means of a plate having a plurality of holes with a spacing similar to that of said nuts, each of said holes having a periphery geometrically dissimilar from that of said nuts such that said plate cannot be fitted over said nuts without deforming the periphery of said holes; said method comprising the steps of placing said plate over said pre-tightened nuts with said holes disposed in alinement with said nuts, and then deforming the periphery geometrically of each of said holes at, at least, one corner of one of said nuts by forcing said plate over said nuts.

3. The method of securing a pair of members together by means of a plurality of fixedly-spaced polygonal nuts or the like and securing said nuts against rotation by means of a plate having a plurality of holes with a spacing similar to that of said nuts, each of said holes having a periphery geometrical-1y dissimilar from that of said nuts such that said plate cannot be fitted over said nuts without deforming .the periphery of said holes; said method comprising tightening said nuts to a predetermined extent without regard to their ultimate rotative positions, placing said plate over said nuts with said holes disposed in alinement with said nuts, and then deforming the periphery geometrically of each of said holes at, at least, one corner of one of said nuts by forcing said plate over said nuts.

4. In combination with a pair of members secured together by a plurality of spaced pre-tightened polygonal nuts or the like, a locking plate having a plurality of holes therethrough with a spacing similar to that of said nuts for locking said nuts against rotation, the holes in said plate having an initial periphery geometrically dissimilar from that of said nuts such that said plate cannot be disposed over said nuts without deforming the periphery of said holes; said plate being disposed over said nuts with the periphery of each of its holes extending about and being interlockingly engaged by at least one corner of the nut associated therewith so that the plate material adjacent said corner is deformed and stressed in a manner similar to that resulting from forcing said plate over said nuts.

5. In combination with a pair of members secured together by a plurality of spaced pre-tightened polygonal nuts or the like, a locking plate having a plurality of holes therethrough with a spacing similar to that of said nuts for Iocking said nuts against rotation, the holes in said plate being initially circular with a diameter less than the maximum width across the corners of said nuts whereby said plate cannot be disposed over said nuts without deforming the periphery of said holes; said plate being disposed over said nuts with the periphery of each of its holes extending about and being interlockingly engaged by at least one corner of the nut associated there-- REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 175,427 Cobb Mar. 28, 1876 765,247 McComb July 19, 1904 946,055 Kittredge Jan. 11, 1910 1,125,545 Jackson Jan. 19, 1915 1,479,358 Behringer Jan. 1, 1924 1,571,511 Dorsey Feb. 2, 1926 2,385,777 Ebert Oct. 2, 1945 FOREIGN PATENTS Number Country Date 315,505 Germany Sept. 28, 1920 324,061 France Dec. 2, 1902 

